This invention relates to a unique receiver system which improves the Signal-to-Noise ratio capability of receiving signals, compared to conventional receiver practices, and by processing stored received data in near-real time, reduces the inherent affect of thermal noise. This dramatic improvement in the performance affords greater flexibility with respect to several relevant parameters, such as for example, bandwidth, access time, and multiplex ability and accordingly is beneficial in a wide range of commercial and military markets. The invention is applicable to a variety of wireline telecommunications media and data applications including the “Internet”.
There are few communication systems that cannot benefit from a significant reduction in the inherent thermal noise that results from necessary amplification. Previous efforts have been expended to conceive, improve and develop a “wireless” antenna and receiving system that has a dramatically improved signal-to-noise ratio and related characteristics. In this process extensive software programs were conceived and developed for both simulation and solution-to-problem purposes. These techniques have been adapted to wired communication. The result includes means for greatly improving the signal-to-noise ratio that can be obtained from a sequence of digitally converted received signals that are stored and then processed in a wired system suited to the “INTERNET”.
The description herein describes the signal-to-noise improvements and involves both “hardware” and “software”. These unique features provide the potential for increasing channel capacity and other performance improvements. These opportunities for improvement occur at several links in the operation such as with the service provider(s) and at various “gateways” that receive the communicated modulated signal.
Processing is achieved using modem integrated circuits in an off-line manner that does not adversely compromise the bandwidth of the system. The time for such processing results in a “transport” time delay, which can be made tolerable. The resulting “near real time” performance provides the potential to obtain dramatic S/N improvements beyond that predicted by classic analog developed theory.
Thermal noise is introduced as a result of necessary amplification in the reception of a signal; such noises are usually a limiting factor in the ability to identify a “weak” signal. If such noise is substantially reduced, there results a potential for improving the receptivity of the signal, thereby also allowing for tradeoffs in parameters such as bandwidth and optimization of multiplexing abilities. When transferring packets of digital data, as used in transmitting Internet information, the noise affects the reading in that detecting each “plus” digit so as to be able to distinguish it from the absence of signal which constitutes a “minus” digit. As noise is reduced, weaker digits can be read more reliably and a lower “error rate” results. For a given “acceptable error rate”, the improvement in signal-to-noise can be used to increase the number of signals that can be multiplexed and maintain the same error rate and thereby increase the system capacity.
The unique techniques used in the processing are intended to be performed digitally to obtain the desired precision and preserve the numerical accuracy. It is consistent with such processing to convert both the signal and the noise introduced at reception to a digital format. Thus, despite the fact that the packets are already digital, it is more consistent to restore the signal to analog and then convert the analog signal plus noise to digital signal-plus-noise. This, in some respects may be unnecessary because the digital packet that is corrupted by the analog receiver noise probably will reduce to the same digital numbers as the more pedantic approach of converting to all analog and then conversion back to digital. These options are discussed later in connection with block diagrams (FIG. 1 and FIG. 3).
The ability to reduce thermal noise limitations that are inherent in any receiving system, beyond the results obtained by averaging several trials, is unique. Such achievement is facilitated by the digital nature of the process (specifically the “storage” of the digitized numbers). However, “being digital” does not in itself produce S/N improvement. Rather, it is the subsequent use of unique iterative processing using an inherent storage and a matrix that serves as a “change sensor” that has unique properties herein described that causes each step to act as a part of a converging iterative procedure with logic that applies to each of the several iterations.
The improvement over merely averaging the noise is the result of improving the “entropy” of the overall process. The processing steps bring a degree of order not initially present. Such order is the result of forcing each and every sample of the noise in a special numerical array to change polarity in a carefully defined manner. This occurs during successive trials, each of which serves as a row of the stored matrix. From this stored information, inherent in the digital matrix, a unique iterative processor, to be described later, will extract the desired information by off-line processing using the signal plus noise flow shown in FIGS. 8 and 9.